So, I decided to tackle the spark plug replacement DIY today. Everything went well until I was buckling down the last ignition coil and the 10mm bolt snapped. Apparently my torque wrench has stopped working correctly (stopped giving me the audible click - I have checked it since, and it for sure gave out). I have tried making a groove in the top and backing it out by hand, no luck. I then went on to try Grabit SpeedOut bits to try an engage it and back it out that way. The tip of the bit broke off engaged into the bolt. I'm out of ideas. I've never had this much trouble getting a bolt out. Does anyone have any ideas? Should I just take it in at this point? Is it safe to drive with the coil not bolted down completely (short term)? Pictures for reference:

 

Maybe use and Easy Out or possibly drill it out and retap it.

 

Try using a pin punch to get the grab it bit out and use a left-hand drill bit drill then heli coil, if not just silastic the under the top of the coil if it's a tight fit it won't go anywhere good luck.

 

Ended up dropping it off at my mechanic last night. He took a look this morning and said risk wasn’t worth the benefit to try and get it out. Usually the coil will hold in place. Worst case scenario is a misfire, which he said just pull over and push it back in. If it happens a lot then think about fixing it, but the risk isn’t worth the benefit at this point.

Now I’m just wondering if there is something I can put over it/on it to “stick” it down in place just a little. But idk what would be safe and still stick to the engine but be able to be pulled off for maintenance when needed. By silastic do you mean silicone?

 

Did you try a reverse drill bit? I had this happen on a drain bolt on my X5 once. Slowly but surely drilled the bit into the bolt.....then reverse out basically unscrewing it out or pulling it out. It worked. It was a messy pain in the *** though.

 

Great tips right here:

 

Drill a smaller hole and tap it for an M4 or M5 bolt. Yes, you can drive it like that. The coil end snaps into the top of the plug slightly. It may never pop out but the bolt that broke off makes sure of that. I’ve never used torque wrench on those bolts, nor the plugs for that matter.

 

​​​​​​​I did try that, used some "speedout pro" bits. Got the hole drilled for the reverse put, it grabbed, hope was restored, then the tip broke off in the bolt... so I'm pretty sure without completely drilling it out and retapping it, it's there for good.

 

OP, not a dig on you, simply something to think about. Any single bolt install like this only needs to stay in place until the next time you take it out. Like a gas cap for example. My advice is use a stubby ratchet and know that when a bolt stops turning, something must give, it will only stretch so much before it breaks and snug is enough.

The bolt securing the coil needs just a few threads to hold it (its own diameter) in depth to hold it. If you want it out, there are options.

1) Grind the boss down (aluminum) using a cut off disc until you can get to that hardened bit and chip it out.
2) be aggressive and cut a deep slot through the boss and into the center of the bolt making a screwdriver slot. This isn't a camshaft or flywheel, that bolt only needs to stay until the next time it comes out.
3) what ever you grind off the boss, add a spacer or washer so the coil ear doesn't snap off.

3B) replace valve cover.
Ping me if you need more information.

 

14 Pc 1/2" Heavy Duty Impact Screwdriver Driver Set